The first task in figuring out the feasibility of Noah’s Ark is finding the size of the boat. This seems like it should be a simple question to answer if you believe the Bible is literally true, because the dimensions of the Ark are one of the few details spelled out in the Bible:

“The length of the ark shall be three hundred cubits, the breadth of it fifty cubits, and the height of it thirty cubits.”

Genesis 6:15, KJV

So the only relevant question is how big the cubit was. This actually wasn’t that controversial when I first became interested in Noah’s Ark. If your Bible gives the size of the Ark in modern units, it likely gives dimensions of 437.5 feet X 72.9 feet X 43.7 feet (133m x 22m x 13m), or a rounded equivalent such as 450 feet X 75 feet X 45 feet. This conversion uses 17.5 inches for the Hebrew Cubit, which is based on the dimensions of Israelite buildings found by archeologists in Palestine[1]. These are the most common dimensions you will find in YEC literature, including The Genesis Flood and Noah’s Ark: A Feasibility Study. They were also used in official Answers in Genesis presentations as late as 2009 [2].

However, when Answers in Genesis was designing the Ark Encounter, they decided to use a larger cubit, which reopened a very old debate. The cubit was originally approximately the length from your elbow to the tips of your fingers, and even when it became standardized the standard length varied by culture. And because critics have been arguing that the Ark was too small to fit all of the animals since ancient times, people have been arguing for a larger cubit for millennia.

Interestingly, the largest cubits I’ve found record of are from times when the cubit was still a common measurement. Origen of Alexandria (185 – 253 CE) suggested that Noah may have used the Egyptian geometric cubit, which was 6 regular cubits long[3], which would make the ark 2625 feet (800m) long, more than 8 football fields! I can find no record outside of Origen for the Egyptian geometric cubit being this long, and neither could John Wilkins in 1668, who further points out that if this cubit was used for Goliath, his head would have been much too big for David to cut off and carry to Jerusalem [4]! This was presumably just a misunderstanding on the part of Origen. However, he wasn’t alone. The Ancient Babylonian historian Berosus (290–278 BCE) reportedly gave a size for the Ark equivalent to 3000 feet long [5].

Moving on to more modern claims of absurd sizes, it is common to hear the justification that back in the days closer to creation, when everyone lived to be several hundred years old, so maybe people were also taller back then, and thus had longer forearms. So Noah’s cubit may have been larger than the cubits 2000 years ago. However, this is something you’re more likely to find on Facebook or hear from a random preacher with a megaphone on a street corner than a major YEC organization. Most serious Ark nerds reject this argument because the human body plan runs into structural problems if it is made much taller than about 8 feet, and Noah could not have been the tallest man in the Bible because there are giants in the Bible including Goliath, and possibly the “nephalim” (translated in the KJV as “giants”). Furthermore, to account for all of the human/hominid fossils a good portion of Noah’s close descendants must have been preserved in the fossil record, and all of them are around the size of modern humans or smaller. Wilkins also been noted that if humans were bigger in the old days, the animals presumably would have been too, which means they would take up more space [6].

For more realistic sizes, another assertion I’ve heard is that because Moses was raised in Egypt, and Moses allegedly wrote Genesis, the dimensions would presumably be based on the units he grew up with. The Egyptian Royal Cubit was about 20.6 inches. A similar size of 20.4 inches is obtained by positing a Hebrew Royal Cubit, usually justified using these quotes from the book of Ezekiel:

“In the man’s hand was a measuring rod six cubits long, each being a cubit and a handbreadth” (Ezekiel 40:5)

and

“These are the measurements of the altar in cubits (the cubit is one cubit and a handbreadth)” (Ezekiel 43:13)

This is where the 20.4 inch cubit used for the Ark Encounter comes from. They suggest that the Ark, being like an altar, would be built with the royal cubit.

However, if you consistently use these larger cubits consistently throughout the Bible you run still run into some logistical problems. For example, there is an altar in Exodus 27:1. Exodus was also allegedly written by Moses, so whether the royal cubit was used because of Moses’s upbringing or because altars are holy, either way this altar should use the royal cubit, right? But the height of the alter is three cubits, which with either royal cubit would be over 5 feet. A 5 foot tall altar would be difficult to use from the ground, and Exodus 20:26 prohibits using steps to reach the altar due to the risk of up-robe flashing the public! The 17.5 inch cubit makes more sense.

[1] R. B. Y. Scott, “Weights and Measures of the Bible,” The Biblical Archaeologist, pp. 21-40, 1959.

[2] J. D. Browning, “Noah’s Ark – A Feasibility Study,” October 2002. [Online]. Available: http://njbiblescience.org/presentations/Noahs%20Ark%20-%20A%20Feasibility%20Study.pdf.

[3] Augustine, City of God, P. SCHAFF, Ed., Hippo Regius: WM. B. EERDMANS PUBLISHING COMPANY, 426.

[4] J. Wilkins, An Essay towards a Real Character and a Philosophical Language, London: Printer for the Royal Society, 1668.

Wilkins puts the height of Goliath’s head at 9 feet. I’m not sure what cubit size he is using to obtain that. Goliath’s height is either four cubits and a span or six cubits and a span depending on which ancient manuscript you use as a source. Using the 17.5 inch cubit and the head being about 1/5th of the height of the body I get 7.8 feet using 4 cubits and a span or 11.4 feet using 6 cubits and a span. Regardless, the head alone would be bigger than David.

[5] D. Fasold, The Ark of Noah, New York: WYNWOOD Press, 1988. Page 60.

[6] J. Wilkins, An Essay towards a Real Character and a Philosophical Language, London: Printer for the Royal Society, 1668. Page 163.